We Burn as Many Calories as Hunter-Gatherers, So What Makes Us Fat?

Contrary to conventional wisdom, detailed energy measurements show that while hunter-gatherers may be more physically active than the rest of us, they don't burn more calories thanks to their lower metabolisms

We all know why Americans are so fat, right? We too much junk and we sit on our duffs all day.

Perhaps not, a team of international researchers now says. Their new study, examining energy expenditure among one of the world’s last remaining hunter-gatherer populations, seems to debunk our conventional wisdom — at least in part.

While we’ve always assumed that humans’ ancient ancestors must have been more active than today’s modern Westerners — with our office jobs, our cars and our TV sets to keep us sedentary — new measurements of actual energy expenditure are surprising. They show that people in traditional foraging societies do indeed participate in more physical activity, but that their total energy output is almost identical to that of today’s pudgy Westerners. This counterintuitive finding is explained by the foragers’ lower basal metabolic rate: they expend less energy while at rest, even when we compare people of the same size and age.

To gather the startling new measurements, researchers recruited 30 adults from the Hadza hunter-gatherer society, a small population living in the East African country of Tanzania. No society today is truly like the those of our ancestors tens of thousands of years ago, the researchers say, but the Hadza do share some important similarities with our Pleistocene-era forbears.

In particular, the Hadza maintain a traditional foraging lifestyle, hunting on foot using bows, small axes and digging sticks, and without modern tools like vehicles or guns. Their diet includes virtually no processed foods whatsoever. They live off of game that they hunt, and tubers, fruit and honey that they collect.

To measure energy use, participating Hadza adults wore GPS units to track how far they traveled each day. They also wore breath monitors while at rest and while walking to measure their metabolism in each state. And a measure of total energy expenditure was calculated from urine tests, which showed how quickly the study participants could eliminate a chemically altered water given to them to drink by the researchers. Then those measurements were compared to similar energy-expenditure measurements from 68 men and women who live in the U.S. or Europe, and also to data from farming communities in Bolivia, Nigeria and Gambia.

Contrary to even the researchers’ expectations, the scientists write, energy-expenditure measurements from the Hadza looked pretty similar to measurements elsewhere.

In fact, even though total energy expenditure did vary considerably by age, gender and by body size, as anticipated, when the researchers looked at men of the same age who each weighed, say, 130 lbs., there was no discernible difference by lifestyle group in total daily energy expenditure. On average, the Hadza were much smaller than the Westerners, both in height and in weight (130 lbs. was at the high end for Hadza males). But statistical analysis suggests that the basic relationship between energy spent and lean body mass — not including the Westerners’ extra fat pounds — was essentially the same across societies, and across people big and small.

Those results are all the more surprising because the Hadza did appear to expend much more energy in physical activity, as they hunted and foraged. But activity differences did not translate into differences in total energy use. What’s more, even among members of the same society, Hadza people who walked a long way each day did not have measurably higher total expenditure than individuals who did not walk so much. It seems that people’s metabolisms may compensate somewhat for activity level.

The new findings seem to contradict popular beliefs that weight management is simply a matter of balancing what we eat with enough purposeful physical activity.

“The similarity in [total energy expenditure (TEE)] among Hadza hunter-gatherers and Westerners suggests that even dramatic differences in lifestyle may have a negligible effect on TEE,” the authors conclude in their study, which is published this week in the journal PLoS One.

While the authors don’t look at diet in much detail, they add that their findings suggest that high energy intake — eating too much — is responsible for the West’s obesity epidemic, rather than too little energy expenditure. They do note, however, that physical activity is well-known to have many beneficial health effects in addition to any role in weight management.

Ultimately, what the study authors may have uncovered is that people are more similar than we previously realized. Across dramatically different societies and landscapes, human bodies function similarly.

“We hypothesize,” they write, “that [total energy expenditure] may be a relatively stable, constrained physiological trait for the human species, more a product of our common genetic inheritance than our diverse lifestyles.”

Science may be able to save us. Not as in making new things to save us but as in a concept.

Science shows that pleasure and pain are merely signals that indicate things. Try thinking of them as just being signals that indicate things and not as the be all end all of existence and you may find you have more willpower to resist cravings for food. Make freedom more important than pleasure and pain. Freedom to know you are doing your best to make good use of your body and mind. If it's hard even try to experiencing negative emotions when you do things you crave. Cringe as you bite into fatty food. Spit it out as if you were sick. In time your preferences will be different.

Our weight problems are due to endocrine illness and hormone imbalances brought on by eating unhealthy foods full of xenoestrogens and toxins, taking medications we don't need, cooking in plastic, stress and not getting enough of the right kinds of exercise. It's not as simple as calories in, calories out.

Where the Koi-San hunting bacon and gathering cheese? I know that eating a proper balance of carbs and protein with vegetables in smaller meals, 4-5 times a day and exercising daily makes me drop weight faster than a crackwhore. I did it beginning this year and never felt better. Now Im back at my original weight because I stopped a couple of months back. Eating properly and exercising works, but I am LAAAAAZZYYY! I know what I need to do to loose weight, but I am just plain lazy. Go try a Body For Life or some set 3 month program/challenge. You would be amazed at what you can acomplish.

Hmmm....those facts are something to look into. As suggested, "high energy intake — eating too much " is why we gain are gaining weight. That is a vital point there. the availability of food is superfluous these days. One call or click, fetches a sumptuous meal, though highly contagious for gaining weight. And our weakened will powers, effect of stress and ever increasing cravings just flair that eating passion more.

Although mildly surprising, the idea that metabolic rates are basically common is not a huge leap. I suspect that the hunter-gathers also are more effective at conserving energy than their piggy industrial counterparts. The industrial notion of continual human output is a perversion of having domesticated machines only recently in the industrial age and then mistaken humans for machines aka "employees". Consider that cats are amazing quick and talented animals, master predators, but they also sleep a lot so they do not have to waste unnecessary energy hunting and preying. Why should humans be any more stupid than cats, unless you mean french fry swilling "advanced" societies that really do believe humans are machines to be clocked to the last second, or maybe outsourced.

The reason Hadza's metabolism is lower is because they eat less. It's simple survival tactics used by your body: If it's consistently low on energy, it will adapt by lowering it's metabolism to make due with less. In other words, your body is saying "Crap, don't have a lot of energy to burn, better conserve!" That's why skipping breakfast is detrimental to weight loss: many people think they'll lose weight because they skipped the calories but skipping tells your body "I have little/nothing to burn, so lower my metabolism and preserve all the fat I have, it's survival time!" (More: http://winterbluescoach.com/sk.... Likewise, eating a lot will rev up your metabolism. This is simplified (time of day not taken into account for e.g.) but the basic principle hold true.

Thus, Hadza's have lower metabolism but a higher exercise-related energy expenditure due to copious exercise, while "pudgy westerners" have higher metabolism (because they eat a lot) but a lower exercise-related energy expenditure due to little to no exercise. Hence, the similar TTE's.

And just to be clear, exercising does not lower basal post-workout metabolism. Also, contrary to popular belief, it does not increase it either (http://www.msnbc.msn.com/id/30.... You burn what you burn during exercise and quickly return to resting levels after.

It's a shame the article didn't stress the connection between metabolism and food intake. Exercise may affect metabolism slightly since you're burning calories during exercise obviously, but I think the effect is negligible compared to the effect of food intake, unless you're running ultra marathons everyday. Thus, someone with a small (not too small so as to put the body into survival mode), healthy diet who doesn't exercise has a better chance of losing weight than someone who exercises regularly but overeats. At least the article got that right: American's are fat because they eat too much, not because they exercise too little. Don't get me wrong, I love to exercise/work out but I do it for the countless other health benefits and of course, for the ladies ;) And don't even get me started on sugar and refined carb consumption, that's a whole other story. You might be thinking "but you're contradicting yourself because above you said eating more increases metabolism so shouldn't American's/Westerners be skinny due to high metabolism?!" Well no. The point is that even with their high metabolism, the majority of us still eat waaayyy more than we can burn. Period.

I like this article, very interesting and thought-provoking. Personally, I think it's important that we grab a few pointers from our hunter-gatherer ancestors, and the best way to do so is to replicate their diet, which is why I recommend the Diet Solution Program, written about in this great review: http://fantasticfitnessreviews...

This study tries too hard to confuse the relationship between overeating fatty, sugary, unhealthy food and individuals/communities who perhaps have a healthier lifestyle and relationship with food.

Immediately I think of the phrase"Lies, damned lies, and statistics" where persuasive power of numbers can tell any story. Should we however focus on the fact that the hunter gatherers will certainly have some lean time as well as some time of fat times. Therefore the game and the catch will not always be there, thus making it vitally important form them to evolve and a system that learns to hang on to the energy for as long as possible. So if after a long days work, they have used up relatively the same amount as their fat counterparts in the USA, well..it shows how efficient their system is and with a relatively low metabolism. Should this be otherwise they would simply burn up everything they eat in a hurry and be starving hungry the next day.

Us in our modern civilization with over supply of processed junk foods hand have also adapted in the opposite ways so that in order cope with such richness in food consumption our bodies attempts to burn off the excess. So in reality, we appear to burn the same amount of calories as our skinny counterparts. Fact!

The report uses statistical illusionary trick to back up a bit of a ‘mad-notion’ Nothing else! If it was 1st of April I would simply chuckle!

Yup, I'm fat because I eat food-like stuff that packs an unnatural amount of calories into a serving the size of your fist. And while illegal drugs are outlawed because of the damage they do, the non-food items that pack our shelves and our diets are legal, in spite of the damage they do - AND marketed to children.

When will we start treated added sugar and fat the way we treat tobacco: Tax the heck out of it, forbid advertising, rip away any shred of legitimacy, and keep it out of public places?

Lots of generalizations and ignorance in these comments. It's not a simple eat less, more more concept, sorry. Yeah, may have worked for you or your cousin or your uncle, but it's not that simple. I gained weight, get this, because I was eating too little. I actually had to add 500 more calories to my day before any of the weight would go away. I also had to give up anything and everything processed or starchy and only focus on organic produce and grass-fed meats. Why? The increased traditional vegetable consumption hurt me because certain pesticides act as an estrogen (a problem for any overweight female). Traditional meats are fed corn, not their natural diets of grass, which produces meat high in bad Omega 6s when we should be eating higher amounts of Omega 3s. Grains are genetically modified and were actually increasing an insillin response in my body. But most of all, we're all different and need to find the right diets for our unique hormones and chemistry.

This is an interesting article in that it compared hunter-gatherers (thin and exercising) to Americans (obese and sedentary), and found that both groups expend the same amount of energy. These results are not new. We published a paper with very similar results in 2004. Here is a link to that paper: https://www.researchgate.net/p...

We compared thin and obese American women. Obese people resting expend the same amount of energy as thin people exercising. Just like the new paper we concluded that obese people are fat because they eat too much.

The big difference is the food available to hunter-gatherers and present day Americans. Calorie dense foods (fats, sugars) taste wonderful to humans, but were difficult to come by for hunter-gatherers, and required some work to acquire (think honey, eggs, meat). Modern Americans have constant easy access to calorie dense foods.

Because of the easy access to calorie dense foods we have to discipline ourselves to not overeat these types of food. That is part of the reason fruits and especially vegtables are important. Not only do they contain mico-nutrients (vitamins and minerals) and fiber, but they are not calorie dense. They take up more space in the stomach and satisfy hunger but are lower in calories.

Physical activity is important for many reasons, but only as an aid to dieting. The food is key.

Good research, lousy reporting. The research does NOT debunk conventional wisdom. "Conventional wisdom" is identical to scientific results: people are fat because the eat too many calories AND don't exercise. It's taking in more than you burn. The research showed that it's not just amount of exercise, which no one ever said. Ms. Blue had done everyone a disservice with her misleading description, perhaps in an attempt to have a catchy into.

We all know why Americans are so fat. It is because we eat too much junk food and we sit on our chairs, sofa, bed all day. Our ancestors are more active in hunting before they could they their own food. While now, we are just going to reach it out from the our fridge and sit back and relax all day long.

There is so much these researchers didn't look at. They didn't look at diet at all. We eat white bread and pasta and GMO corn and soy and pesticide-saturated foods. They eat meat and vegetable matter that is pure and free from synthetic chemicals.

The researchers did not look at the types of energy expenditure. Walking or running versus stressing over the demands of your job and life. Stress destroys your adrenals and hunter gatherers have far less stress than we have in industrialized nations. It's not surprising that they expend less energy. Anthropologists have known for years that H/G groups work half as many hours as we do in industrialized nations. I don't think these researchers consulted with cultural anthropologists at all. This isn't news.

Jacqueline first of all congrats! And way to go, you are doing fantastic! Keep it up :) Secondly, I'll add my voice to yours for being one of the weird people who shafted their metabolism by eating too little (thanks to all the people like the commenters below who keep chanting "you're fat because you eat too much!") I have been obese for many years. I have also been dieting for basically my entire adult life. I got to the point where I was eating about 600 - 800 calories a day, sometimes not at all, and still gaining weight. I went on a medically approved eating plan that added healthy calories up to 1400/day and for the first time ever the weight started just coming off. It absolutely can happen and metabolism is never as simple as just calories in vs calories out. Good luck in the future!

Total BS! Go ride and jog 3-4 days a week for 35-45 minutes and you WILL lose weight PERIOD. Show me ANY research where people that exercised regularly gained weight and didn't become fit. Quite making excuses. It takes WORK. Nobody wants to hear that. It also takes TIME. Like 3 years. P90x will give you some quick results but after that it takes WORK.

*Munches on trail mix of raw almonds and unsweetened cranberries* Amen, brother! With my bad genetics (mother is type II diabetic, father is late-onset type I), my blood sugar started going out of control at the age of 20, when I was a trained road racing cyclist. Obviously, I wasn't overweight at the time. However, my diet, despite being lower than average in sugar, was full of white starches. Fast forward 8 years later... I'm a bit less physically active these days, but my diet has essentially zero white starch in it, and I keep my "guilty pleasure" sugar consumption to <50g/day. My fasting blood glucose has since never gone above 80 mg/dL, 30 points lower than it was 8 years ago.

That's a very interesting interpretation and seems to be exactly opposite of what the research indicates. But believe what you will.

From the article:

“We hypothesize,” they write, “that [total energy expenditure] may be a relatively stable, constrained physiological trait for the human species, more a product of our common genetic inheritance than our diverse lifestyles.”

The difference in the make up of the fat in the grass fed meat versus the grain fed meat. Grass fed meat is higher in Omega 3 fatty acids, while grain fed is higher in omega 6. Here is a link that contains a list of references.

Give me a quick minute and I'll find you the research that shows that this doesn't work for everyone. This is because increase exercise = increased appetite. You're canceling out the calories burned with the extra calories you're eating. It's very difficult to go from not exercising to exercising routinely without increasing your food/caloric intake.

Exercise should be used to stay fit and healthy, but not necessarily done alone to lose weight.

I was overweight for decades and lost about a third of my body weight by reducing calories. When people who knew me while I was heavy ask how I did it and I reply, "I stopped eating so much food" the conversation stops cold because nobody wants to hear that reducing food intake is the answer. Americans like solutions that are quick and easy. Dieting is neither of those things. Dieting takes time, discipline, and thought.

Jacqueline's story is interesting because she asserts that she actually had to add 500 calories to lose weight. While that is interesting I imagine that reducing calories works for most.

After I lost the weight I came to realize just how much WORK it is to be overweight. Just about every physical activity is so much easier now.

Hi Dina and Jackie. Congratulations Jackie on finding what works for your body. Too bad we don't all come with owner's manuals because I DO think there are variations in the way people metabolise food. I hope you did not think I intended disrespect or doubt, but only that I think calorie reduction probably works for most of us.

I am biased because Jackie is my sister, but I can tell you that she had cut out calories so low that she actually destroyed her metabolism. She lost all the muscle that she built as a competitive speed cyclist when she watched calories. Plus none of us could be around her because she was lethargic all the time and looked sick and was so cranky. I only tell you this because I thought the same way you did. Several nutritionists told her the same thing. I can eat anything and not gain so I couldn't understand and thought she had no will power, thought she was lazy. I think her point was that she found something that worked for her, and it wasn't by following what nutritionists, let alone random strangers online, told her to do.